It's not just about money for the journalists themselves. Visit a journalism school and you'll find
very few students there looking to maximize their earnings.
It's a lot like other fields such as science or arts. People entering these careers knowlingly accept low pay and/or difficult working conditions in exchange for other kinds of satisfaction. For some it's intellectual curiosity; for others its artistic ambition or applause.
For journalists, it's the psychological satisfication of using political influence to spread their beliefs to others.
The actions of journalists cannot be understood according to a simple profit model. (The actions of their bosses can - they hire journos who will accept low pay, with the implicit exchange that those journos can use the position to satisfy their activist impulses. Fanatics work for cheap.)